Radical-neutralizing coating for a lubricant system

ABSTRACT

A method may comprise preparing a radical-neutralizing composition comprising a cerium compound and a carrier; applying the radical-neutralizing composition to a passageway surface of a lubricant passageway in a lubricant system component; and/or drying the radical-neutralizing composition to form a radical-neutralizing coating on the passageway surface comprising cerium oxide.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation-In-Part of, and claims priority to,and the benefit of U.S. Ser. No. 14/887,218 filed Oct. 19, 2015 andentitled “CHEMICAL SCAVENGING COMPONENT FOR A FUEL SYSTEM,” which ishereby incorporated by reference in its entirety.

FIELD

This disclosure generally relates to radical-neutralizing coatings inlubrication systems.

BACKGROUND

Hydrocarbons in lubricant systems often comprise dissolved oxygen. Inthe presence of heat, the hydrocarbons and oxygen may form moleculeshaving free radicals, such as alkyl and/or alkoxy radicals, which mayreact with the inner surfaces of lubricant systems to form carbonaceousdeposits, such as coke or varnish. Such carbonaceous deposits may causeblockages within the lubricant system.

SUMMARY

In various embodiments, a method may comprise preparing aradical-neutralizing composition comprising a cerium compound and acarrier; applying the radical-neutralizing composition to a passagewaysurface of a lubricant passageway in a lubricant system component;and/or drying the radical-neutralizing composition to form aradical-neutralizing coating on the passageway surface comprising ceriumoxide. In various embodiments, preparing the radical-neutralizingcomposition may comprise combining cerium nitrate in the carrier. Thecarrier may be at least one of water or a mixture of ethanol andpolyethylene glycol. Applying the radical-neutralizing composition tothe passageway surface may comprise dipping the lubricant passagewayinto the radical-neutralizing composition. In various embodiments,drying the passageway surface may comprise calcination of theradical-neutralizing composition at a temperature ranging from 446° C.to 997° C. In various embodiments, the radical-neutralizing coating maycomprise a coating thickness ranging from one nanometer to onemicrometer. The radical-neutralizing coating may comprise a plurality ofcerium oxide nanocrystallites each having a size ranging from onenanometer to five nanometers.

In various embodiments, a lubrication system may comprise a lubricantsystem component comprising a lubricant passageway defined by apassageway surface, wherein the lubricant passageway may be configuredto receive a lubricant; and/or a radical-neutralizing coating coupled tothe passageway surface comprising cerium oxide, wherein theradical-neutralizing coating has a coating thickness ranging from onenanometer to one micrometer. In various embodiments, theradical-neutralizing coating thickness may range from 0.2 micrometer toone micrometer. In various embodiments, the radical-neutralizing coatingmay further comprise a dopant. The dopant may be at least one oflanthanum or zirconium. In various embodiments, the cerium oxide maycomprise between 50% and 99.9% by weight of the radical-neutralizingcoating. In various embodiments, the dopant may comprise between 0.01%and 50% of the radical-neutralizing coating. In various embodiments, thedopant may comprise between 0.01% and 10% of the radical-neutralizingcoating.

In various embodiments, a lubrication system may comprise a lubricantsystem component comprising a lubricant passageway defined by apassageway surface, wherein the lubricant passageway may be configuredto receive a lubricant; and/or a radical-neutralizing coating coupled tothe passageway surface comprising cerium oxide, wherein theradical-neutralizing coating may comprise a plurality of cerium oxidenanocrystallites each having a size ranging from one nanometer to fivenanometers. In various embodiments, the size of each cerium oxidenanocrystallite may range from one nanometer to two nanometers. Invarious embodiments, the size of each cerium oxide nanocrystallite mayrange from two nanometers to five nanometers.

In various embodiments, the radical-neutralizing coating may furthercomprise a dopant. In various embodiments, the dopant may be at leastone of lanthanum or zirconium. In various embodiments, the cerium oxidemay comprise between 50% and 99.9% by weight of the radical-neutralizingcoating. In various embodiments, the dopant may comprise between 0.01%and 50% of the radical-neutralizing coating. In various embodiments, thedopant may comprise between 0.01% and 10% of the radical-neutralizingcoating. In various embodiments, the radical-neutralizing coating maycomprise a coating thickness ranging between one nanometer and onemicrometer.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures. Elements with thelike element numbering throughout the figures are intended to be thesame.

FIG. 1 illustrates a gas turbine engine, in accordance with variousembodiments;

FIG. 2A illustrates a schematic view of a lubricant system, inaccordance with various embodiments;

FIG. 2B illustrates a perspective view of a lubricant system componenthaving a lubricant passageway with a radical-neutralizing coating, inaccordance with various embodiments; and

FIG. 3 depicts a block diagram illustrating a method for disposing aradical-neutralizing coating on a passageway surface of a lubricantpassageway, in accordance with various embodiments.

DETAILED DESCRIPTION

All ranges may include the upper and lower values, and all ranges andratio limits disclosed herein may be combined. It is to be understoodthat unless specifically stated otherwise, references to “a,” “an,”and/or “the” may include one or more than one and that reference to anitem in the singular may also include the item in the plural.

The detailed description of various embodiments herein makes referenceto the accompanying drawings, which show various embodiments by way ofillustration. While these various embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosure, it should be understood that other embodiments may berealized and that logical, chemical, and mechanical changes may be madewithout departing from the scope of the disclosure. Thus, the detaileddescription herein is presented for purposes of illustration only andnot of limitation. Furthermore, any reference to singular includesplural embodiments, and any reference to more than one component or stepmay include a singular embodiment or step. Also, any reference toattached, fixed, connected, or the like may include permanent,removable, temporary, partial, full, and/or any other possibleattachment option. Additionally, any reference to without contact (orsimilar phrases) may also include reduced contact or minimal contact.

In various embodiments, and with reference to FIG. 1, a gas turbineengine 100 is disclosed. As used herein, “aft” refers to the directionassociated with a tail (e.g., the back end) of an aircraft, orgenerally, to the direction of exhaust of gas turbine engine 100. Asused herein, “forward” refers to the direction associated with a nose(e.g., the front end) of the aircraft, or generally, to the direction offlight or motion. An A-R-C axis has been included to illustrate theaxial (A), radial (R) and circumferential (C) directions. For clarity,axial axis A spans parallel to axis of rotation 120. As utilized herein,radially inward refers to the negative R direction towards axis ofrotation 120, and radially outward refers to the R direction away fromaxis of rotation 120.

Gas turbine engine 100 may comprise a two-spool turbofan that generallyincorporates a fan section 122, a compressor section 124, a combustorsection 126, and a turbine section 128. Gas turbine engine 100 may alsocomprise, for example, an augmenter section, and/or any other suitablesystem, section, or feature. In operation, fan section 122 may drive airalong a bypass flow-path B, while compressor section 124 may furtherdrive air along a core flow-path C for compression and communicationinto combustor section 126, before expansion through turbine section128. FIG. 1 provides a general understanding of the sections in a gasturbine engine, and is not intended to limit the disclosure. The presentdisclosure may extend to all types of applications and to all types ofturbine engines, including, for example, turbojets, turboshafts, andthree spool (plus fan) turbofans wherein an intermediate spool includesan intermediate pressure compressor (“IPC”) between a low pressurecompressor (“LPC”) and a high pressure compressor (“HPC”), and anintermediate pressure turbine (“IPT”) between the high pressure turbine(“HPT”) and the low pressure turbine (“LPT”).

In various embodiments, gas turbine engine 100 may comprise a low speedspool 130 and a high speed spool 132 mounted for rotation about an axisof rotation 120 relative to an engine static structure 136 via one ormore bearing systems 138 (shown as, for example, bearing system 138-1and bearing system 138-2 in FIG. 1). It should be understood thatvarious bearing systems 138 at various locations may alternatively oradditionally be provided, including, for example, bearing system 138,bearing system 138-1, and/or bearing system 138-2.

In various embodiments, low speed spool 130 may comprise an inner shaft140 that interconnects a fan 142, a low pressure (or a first) compressorsection 144, and a low pressure (or a second) turbine section 146. Innershaft 140 may be connected to fan 142 through a geared architecture 148that can drive fan 142 at a lower speed than low speed spool 130. Gearedarchitecture 148 may comprise a gear assembly 160 enclosed within a gearhousing 162. Gear assembly 160 may couple inner shaft 140 to a rotatingfan structure. High speed spool 132 may comprise an outer shaft 150 thatinterconnects a high pressure compressor (“HPC”) 152 (e.g., a secondcompressor section) and high pressure (or a first) turbine section 154.A combustor 156 may be located between HPC 152 and high pressure turbine154. A mid-turbine frame 157 of engine static structure 136 may belocated generally between high pressure turbine 154 and low pressureturbine 146. Mid-turbine frame 157 may support one or more bearingsystems 138 in turbine section 128. Inner shaft 140 and outer shaft 150may be concentric and may rotate via bearing systems 138 about axis ofrotation 120. As used herein, a “high pressure” compressor and/orturbine may experience a higher pressure than a corresponding “lowpressure” compressor and/or turbine.

In various embodiments, the air along core airflow C may be compressedby low pressure compressor 144 and HPC 152, mixed and burned with fuelin combustor 156, and expanded over high pressure turbine 154 and lowpressure turbine 146. Mid-turbine frame 157 may comprise airfoils 159located in core airflow path C. Low pressure turbine 146 and highpressure turbine 154 may rotationally drive low speed spool 130 and highspeed spool 132, respectively, in reaction to the expansion exhaustgases.

In various embodiments, gas turbine engine 100 may comprise ahigh-bypass ratio geared aircraft engine. The bypass ratio of gasturbine engine 100 may also be greater than ten (10:1). Gearedarchitecture 148 may be an epicyclic gear train, such as a star gearsystem (sun gear in meshing engagement with a plurality of star gearssupported by a carrier and in meshing engagement with a ring gear) orother gear system. Geared architecture 148 may have a gear reductionratio of greater than about 2.3 and low pressure turbine 146 may have apressure ratio that is greater than about five (5). The diameter of fan142 may be significantly larger than that of the low pressure compressorsection 144, and the low pressure turbine 146 may have a pressure ratiothat is greater than about five (5:1). The pressure ratio of lowpressure turbine 146 is measured prior to inlet of low pressure turbine146 as related to the pressure at the outlet of low pressure turbine146. It should be understood, however, that the above parameters areexemplary of various embodiments of a suitable geared architectureengine and that the present disclosure contemplates other turbineengines including direct drive turbofans.

The next generation turbofan engines are designed for higher efficiencyand use higher pressure ratios and higher temperatures in high pressurecompressor 152 than are conventionally experienced. These higheroperating temperatures and pressure ratios create operating environmentsthat cause thermal loads that are higher than the thermal loadsconventionally experienced, which may shorten the operational life ofcurrent components, including flanges comprised in gas turbine engine100.

Gas turbine engine 100 may comprise lubricant systems throughout inorder to provide a lubricant to the moving parts of gas turbine engine100. The lubricant may comprise hydrocarbons (e.g., a petroleum-derivedproduct), including oil, fuel, or the like. Referring to FIG. 2A, aschematic drawing of a lubrication system 200 of a gas turbine engine isdepicted, in accordance with various embodiments. Lubrication system 200may comprise a lubricant source 205, a lubricant delivery device 210, anengine component 220 which may receive and/or work on the lubricant, anda lubricant delivery system 230 which may facilitate delivery of thelubricant to another location within the gas turbine engine. In variousembodiments, lubricant within lubrication system 200 may be recycledback to lubricant source 205 (e.g., by lubricant delivery system 230)for reuse. Lubrication system 200 may comprise various other components,including lubricant valves, heat exchangers, filters, and/or bearings,each of which may have a passage through which lubricant may travel.

FIG. 2B depicts a lubricant system component 250, in accordance withvarious embodiments. With combined reference to FIGS. 2A and 2B,lubricant system component 250 may be comprised in lubrication system200, and may be a component through which a lubricant may travel. Forexample, lubricant system component 250 may be an example of lubricantdelivery device 210, or a part of engine component 220. To providevarious examples, engine component 220 may be an airfoil and lubricantsystem component 250 may disposed therein; engine component 220 may be aheat exchanger designed to cool a lubricant 259 flowing therethrough andlubricant system component 250 may be one of the cooling tubes of theheat exchanger; engine component 220 may be a bearing and lubricantsystem component 250 may be a bearing cavity. Lubricant system component250 may comprise a shell 253 with a lubricant passageway 256 disposedtherein and/or therethrough. Lubricant passageway 256 may be any spacewhich receives a lubricant 259. Lubricant 259 may travel through and/orin lubricant passageway 256. In various embodiments, lubricantpassageway 256 may be defined by a lubricant passageway rim 262 and apassageway surface 265 spanning the length of lubricant system componentand lubricant passageway 256.

The hydrocarbons in lubricant 259 traveling through lubrication system200 and lubricant system component may be exposed to heat and dissolvedoxygen. Radical-neutralizing coating 268 is disposed along the length oflubricant passageway 256 and passageway surface 265. Thus,radical-neutralizing coating 268 tends to act to neutralize freeradicals, such as alkyl and/or alkoxy radicals, which may form due toreactions between the hydrocarbons and dissolved oxygen. In variousembodiments, radical-neutralizing coating 268 may comprise cerium oxide,which may be reactive with the radicals in lubricant 259, neutralizingthem such that the radicals are unable to react with passageway surface265 and create deposits within lubricant passageway 256. The ceriumoxide in radical-neutralizing coating 268 may neutralize the radicals inlubricant 259, while regenerating itself such that such a reactionbetween the cerium oxide in radical-neutralizing coating 268 and theradicals in lubricant 259 does not cause deterioration fromradical-neutralizing coating 268. The reaction mechanism may be asfollows: (1) upon formation in air (e.g., oxygen (O₂)), the cerium oxidein radical-neutralizing coating 268 has an oxidation state of plus-4(cerium(IV) oxide (CeO₂)); (2) a hydrocarbon molecule in lubricant 259(having a chemical structure of RH, where R is an alkyl grouporiginating from hydrocarbon lubricant molecules) may react withcerium(IV) oxide; (3) as a result, the cerium(IV) in the cerium(IV)oxide may be reduced to cerium(III) by the hydrocarbon molecule,producing cerium(III) oxide (Ce₂O₃) and an alcohol (ROH), the alcoholbeing a stable product that does not pose a risk of creating depositswithin lubricant passageway 256; (3) an alkoxy radical in lubricant 259(having a chemical structure of RO.) may react with the cerium(III)oxide; (5) as a result, the cerium(III) in the cerium(III) oxide may beoxidized back to cerium(IV), producing cerium(IV) oxide and an alkylradical, the alkyl radical being a product that may not pose asignificant risk of creating deposits within lubricant passageway 256,and the described reaction mechanism may start again. Accordingly,radical-neutralizing coating 268 may be capable of neutralizing alkoxyradicals, while regenerating itself in a continuous cycle. The chemicalequations for the reaction mechanism described above are shown in Scheme1 and Scheme 2 below:

RH+2CeO₂→Ce₂O₃+ROH  Scheme 1

RO.+Ce₂O₃→2CeO₂+R.  Scheme 2

In various embodiments, radical-neutralizing coating 268 may have acoating thickness 271, measured radially, ranging from 1 nanometer (nm)(3.9e⁻⁸ inch) and 1 micrometer (μm) (3.9e⁻⁵ inch). In variousembodiments, coating thickness 271 may be between 0.2 μm (7.9e⁻⁶ inch)and 1 micrometer (μm) (3.9e⁻⁵ inch). In various embodiments,radical-neutralizing coating 268 may be less than 0.2 μm (7.9e⁻⁶ inch).

In various embodiments, the cerium oxide in radical-neutralizing coating268 may be in nanocrystallite form. Radical-neutralizing coating 268 maycomprise cerium oxide nanocrystallites each having a size ranging from 1nm (3.9e⁻⁸ inch) to 12 nm (4.7e⁻⁷ inch). In various embodiments, eachcerium oxide nanocrystallite in radical-neutralizing coating 268 mayhave a size ranging from 1 nm (3.9e⁻⁸ inch) to 2 nm (7.9e⁻⁸ inch). Invarious embodiments, each cerium oxide nanocrystallite inradical-neutralizing coating 268 may have a size ranging from 1 nm(3.9e⁻⁸ inch) or 2 nm (7.9e⁻⁸ inch) to 5 nm (2.0e⁻⁷ inch).

In various embodiments, radical-neutralizing coating 268 may comprisecerium oxide and a dopant. The dopant may be elemental zirconium and/orlanthanum. The presence of zirconium and/or lanthanum may tend tofacilitate the transition of cerium between oxidation states in theoxidation/reduction reaction mechanism described above. In variousembodiments, radical-neutralizing coating 268 may comprise 100% ceriumoxide. In various embodiments, radical-neutralizing coating 268 maycomprise between 50% and 99.9% or 100% by weight cerium oxide. Invarious embodiments, radical-neutralizing coating 268 may comprisebetween 60% and 80% by weight cerium oxide. In various embodiments,radical-neutralizing coating 268 may comprise between 0% or 0.01% and50% by weight dopant. In various embodiments, radical-neutralizingcoating 268 may comprise between 0% or 0.01% and 10% by weight dopant.In various embodiments, radical-neutralizing coating 268 may comprisebetween 1% and 10% by weight dopant. In various embodiments,radical-neutralizing coating 268 may comprise between 10% and 20% byweight dopant.

With reference to FIGS. 2B and 3, a method 300 for disposing aradical-neutralizing coating 268 on a passageway surface 265 isdepicted, in accordance with various embodiments. In variousembodiments, a radical-neutralizing composition may be prepared (step302). The radical-neutralizing composition may be prepared, in variousembodiments, by combining a cerium compound and a carrier (e.g., asolvent). The cerium compound may comprise cerium nitrate, which may bedissolved in the carrier. In various embodiments, the cerium compoundmay comprise cerium(IV) tetramethylheptanedionate (Ce(TMHD)₄) inpreparation for application by atomic layer deposition (ALD), forexample. The carrier may be water and/or a mixture of ethanol andpolyethylene glycol, and/or any other suitable carrier. In variousembodiments, in addition to the cerium compound and a carrier, a dopantsuch as zirconium nitrate and/or lanthanum nitrate may be added to theradical-neutralizing composition. The concentrations of the componentsin the radical-neutralizing composition may be adjusted depending on thedesired coating thickness of radical-neutralizing coating 268 inresponse to applying and drying the radical-neutralizing composition.

In various embodiments, the radical-neutralizing composition may beapplied to passageway surface 265 (step 304). The radical-neutralizingcomposition may be applied by any known technique such as spraying,dip-coating, and/or passing the radical-neutralizing composition throughlubricant passageway 256. For example, the radical-neutralizingcomposition may be sprayed onto passageway surface 265. During spraying,passageway surface 265, or any other substrate upon which theradical-neutralizing composition is applied, may be maintained at anelevated temperature (e.g., ranging from 277° C. (530° F.) to 477° C.(890° F.), or from 327° C. (620° F.) to 426° C. (800° F.). Fordip-coating, the radical-neutralizing composition may be a sol-gel inwhich the lubricant system component is dipped one or more times.Similarly for passing the radical-neutralizing composition throughlubricant passageway 256, the radical-neutralizing composition may be asol-gel. In various embodiments, the radical-neutralizing compositionmay be applied by atomic layer deposition (ALD).

In response to applying the radical-neutralizing composition topassageway surface 265, the radical-neutralizing composition onpassageway surface 265 may be dried (step 306) (e.g., by beingair-dried, or dried under heat (e.g., heat treating)) to formradical-neutralizing coating 268. In various embodiments, drying theradical-neutralizing composition may comprise calcination attemperatures between, for example, 446° C. (836° F.) and 997° C. (1826°F.), or between 527° C. (980° F.) and 727° C. (1340° F.).

The systems and methods described herein are discussed in relation to alubrication system within a gas turbine engine. However, it should beunderstood that the systems and methods described herein may be appliedto any engine, engine component, or device comprising lubricantpassageways which are prone to blockage from the reaction of radicalsforming carbonaceous deposits.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosure. The scope of the disclosure is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A method, comprising: preparing aradical-neutralizing composition comprising a cerium compound and acarrier; applying the radical-neutralizing composition to a passagewaysurface of a lubricant passageway in a lubricant system component; anddrying the radical-neutralizing composition to form aradical-neutralizing coating on the passageway surface comprising ceriumoxide.
 2. The method of claim 1, wherein the preparing theradical-neutralizing composition comprises combining cerium nitrate inthe carrier, wherein the carrier is at least one of water or a mixtureof ethanol and polyethylene glycol, and wherein applying theradical-neutralizing composition to the passageway surface comprisesdipping the lubricant passageway into the radical-neutralizingcomposition.
 3. The method of claim 1, wherein the drying the passagewaysurface comprises calcination of the radical-neutralizing composition ata temperature ranging from 446° C. to 997° C.
 4. The method of claim 1,wherein the radical-neutralizing coating comprises a coating thicknessranging from one nanometer to one micrometer, and wherein theradical-neutralizing coating comprises a plurality of cerium oxidenanocrystallites each having a size ranging from one nanometer to fivenanometers.
 5. A lubrication system, comprising: a lubricant systemcomponent comprising a lubricant passageway defined by a passagewaysurface; and a radical-neutralizing coating coupled to the passagewaysurface comprising cerium oxide, wherein the radical-neutralizingcoating has a coating thickness ranging from one nanometer to onemicrometer.
 6. The lubrication system of claim 5, wherein theradical-neutralizing coating further comprises a dopant.
 7. Thelubrication system of claim 6, wherein the dopant is at least one oflanthanum or zirconium.
 8. The lubrication system of claim 6, whereinthe cerium oxide comprises between 50% and 99.9% by weight of theradical-neutralizing coating.
 9. The lubrication system of claim 6,wherein the dopant comprises between 0.01% and 50% of theradical-neutralizing coating.
 10. The lubrication system of claim 6,wherein the dopant comprises between 0.01% and 10% of theradical-neutralizing coating.
 11. The lubrication system of claim 5,wherein the radical-neutralizing coating thickness ranges from 0.2micrometer to one micrometer.
 12. A lubrication system, comprising: alubricant system component comprising a lubricant passageway defined bya passageway surface; and a radical-neutralizing coating coupled to thepassageway surface comprising cerium oxide, wherein theradical-neutralizing coating comprises a plurality of cerium oxidenanocrystallites each having a size ranging from one nanometer to fivenanometers.
 13. The lubrication system of claim 12, wherein the size ofeach cerium oxide nanocrystallite ranges from one nanometer to twonanometers.
 14. The lubrication system of claim 12, wherein the size ofeach cerium oxide nanocrystallite ranges from two nanometers to fivenanometers.
 15. The lubrication system of claim 12, wherein theradical-neutralizing coating further comprises a dopant.
 16. Thelubrication system of claim 15, wherein the dopant is at least one oflanthanum or zirconium.
 17. The lubrication system of claim 15, whereinthe cerium oxide comprises between 50% and 99.9% by weight of theradical-neutralizing coating.
 18. The lubrication system of claim 15,wherein the dopant comprises between 0.01% and 50% of theradical-neutralizing coating.
 19. The lubrication system of claim 15,wherein the dopant comprises between 0.01% and 10% of theradical-neutralizing coating.
 20. The lubrication system of claim 12,wherein the radical-neutralizing coating comprises a coating thicknessranging between one nanometer and one micrometer.